1. Field of the Invention
The present invention relates to a data storage device, and more particularly, to a data storage device using a magnetic domain wall movement of a magnetic material and a method of operating the data storage device.
2. Description of the Related Art
A minute magnetic region that constitutes a ferromagnetic body is referred to as a magnetic domain. The rotation of electrons in a magnetic domain, that is, the direction of a magnetic moment is identical. The size and magnetization direction can be appropriately controlled by the shape and size of a magnetic substance and external energy.
A magnetic domain wall is a region which separates magnetic domains each having a magnetization direction different from another magnetic domain. The magnetic domain wall can be moved or propagated by an external magnetic field or by a current applied to a magnetic substance. That is, a plurality of magnetic domains having a specific magnetization direction can be formed in a magnetic layer having a predetermined width and thickness, and the magnetic domains can be moved using a magnetic field or a current having an appropriate strength.
The principle of the magnetic domain wall movement can be applied to data storage devices. For example, when magnetic domains pass through a read/write head by a magnetic domain wall movement, an operation of reading/writing data is possible without rotating a recording medium. Since data storage devices using a magnetic domain wall movement have relatively simple structures and small bit sizes to realize highly integration, a very large storage capacity more than 1 Tbit/in2 can be achieved.
However, since such data storage devices are in the early stage of development, several problems should be solved so that the data storage devices may be put to practical use. One of the several problems is that a high current is required for writing. That is, a high current is required in order to reverse the magnetization direction of the magnetic domain.
In addition, a current may disadvantageously leak from the magnetic layer to a write/read head. When a current is applied to the magnetic layer for the magnetic domain wall movement, since the current may partially leak leading to high power consumption, the magnetic domain wall movement may not be smooth.
Accordingly, in order to use data storage device using the magnetic domain wall movement, a writing current density should be remarkably reduced, and a current should not leak to the write/read head.